Dumps information about free space in log part files for the
data node with the node ID
The dump is written to the data node out log rather than to
the cluster log.
REDO part: 0 HEAD: file: 0 mbyte: 2 TAIL: file: 0 mbyte: 2 total: 256 free: 256 (mb) REDO part: 1 HEAD: file: 0 mbyte: 2 TAIL: file: 0 mbyte: 2 total: 256 free: 256 (mb) REDO part: 2 HEAD: file: 0 mbyte: 2 TAIL: file: 0 mbyte: 2 total: 256 free: 256 (mb) REDO part: 3 HEAD: file: 0 mbyte: 2 TAIL: file: 0 mbyte: 2 total: 256 free: 256 (mb)
Additional Information. Each line of the output has the following format (shown here split across two lines for legibility):
A data node's redo log is divided into four parts; thus,
part_no is always a number between 0
and 3 inclusive. The parts are stored in the data node file
directories with redo log part 0 being stored in
D8, part 1 in
so on (see
Section 188.8.131.52, “MySQL Cluster Data Node File System Directory Files”).
Within each directory can be found a
files. The default value for
NoOfFragmentLogFiles is 16. The default size
of each of these files is 16 MB; this can be changed by setting
start_file_no indicates the number of
the file and
start_pos the point
inside this file in which the redo log starts; for the example
just shown, since
part_no is 0, this
means that the redo log starts at approximately 12 MB from the
end of the file
end_file_no corresponds to
the number of the file and
the point within that file where the redo log ends. Thus, in the
previous example, the redo log's end point comes
approximately 10 MB from the end of
total_space shows the total amount of
space reserved for part
the redo log. This is equal to
FragmentLogFileSize; by default this is 16 times 16
MB, or 256 MB.
free_space shows the
amount remaining. Thus, the amount used is equal to
; in this
example, this is 256 - 254 = 2 MB.
It is not recommended to execute
while a data node restart is in progress.